One type of vessel used in hydrocarbon production is an FPSO (floating, production, storage and offloading) vessel, which is of moderate size and widely available. Another type which is larger and not readily available, is an FPDSO (floating, production, storage, drilling, and offloading) vessel. The FPDSO vessel has complex drilling and workover equipment in its middle which usually allows the vessel to weathervane during drilling, production and offloading operations.
Shipyards have dry docks with “time slots” (continuous time periods) reserved for construction of a vessel. The required length of the time slot depends primarily on the amount of steel plate that must be welded together to produce a hull of a desired vessel. There are only a few shipyards available in the world that are capable of building very large vessels such an FPDSO, and it is often difficult to find a yard with a sufficiently long available time slot. A method for constructing a FPDSO which greatly reduced the required length of a shipyard time slot for such construction, would be of value.